I'm not asking about a definition of god - I'm asking about the various ways the word 'atheist' is used.

1) Benjamin Franklin for instance believed in a creator god, but not a personal god. That is, he believed that something made the universe, but not that this 'something' intervened in human affairs, performed miracles, set aside a pleasant afterlife for humans he liked and an unpleasant one for the rest, etc.

He was in strict terms an atheist, but not an adeist. Thus we could call him both atheist and christian.

2) Buddhism doesn't have a god, but it does have spirits, which act much like angels and demons. It's also rather hazy on where the universe came from.

So should we call Buddhists atheists...and adeists? Again, strictly perhaps we should, but I don't think it's useful to distinguish between those who believe in a single, all-powerful supernatural tyrant, and those who believe only in a vast number of less powerful supernatural tricksters.

The difference is of degree, not of kind. Atheism is in this sense a disbelief in the supernatural.

3) Catholics like to say there's no 'real' difference between a protestant and an atheist. Sunni muslims say the same about shia muslims, and vice versa.

We might say there's no practical difference between an atheist and an agnostic. The agnostic may decide not to decide whether there's a god, but have you ever met an agnostic who prayed?

The difference between deciding to not believe and not deciding whether to believe, is a little like the difference between deciding not to eat and not deciding whether to eat. The motivation may be different, but the result is the same.

4) There is a deeper way in which one can reject the notion of a god, and that is to reject the notion of a universal masterplan.

Most christians believe not just that a god made the universe, but that he cares about it, has desires for it, and made it for a reason that wasn't just a whim. For them, the universe has a meaning and a purpose.

Buddhists and jains may not have a god, but they do believe in an overarching plan - as though a god had put one in place. 70% of jews in Israel are happy to publically define themselves as having no religion - but they still treat their right to a homeland as god-given and inviolate.

Pantheism is the notion that god and the universe, in one way or another, are the same thing. Hermetic theology holds that this god-universe is evolving towards a pre-ordained goal - one where the universe becomes self aware, and thus aware that it is god. Or rather that it achieves godhood by this becoming.

Who or what sets this goal...is not entirely clear.

The consciousness of individual humans, and that of human societies, is part of this process. Thus god, to become fully god, needs humans to become fully human. The parallels between the cosmic and the small-scale continue down to the level of chemical reactions.

Hegel was a hermetic philosopher, and Marx was a follower, incorporating into his 'atheist' system the notion that History has a plan, which will culminate in post-capitalist world Communism. Marx's collaborator Engels tried to show that the cosmic schedule of which the political struggle was a part, extended up to the formation of galaxies, across to geological phenomena, and down to electricity and magnetism.

A revolutionary may not believe that god is on their side, but they can still believe that history is a quasi-conscious force with a timetable, and this godlike thing is on their side.

Generally this behind-the-scenes guiding force has a moral aspect. Society after the revolution will be fair, just, ethical. Even among non-revolutionary social progressives, there is the idea that society gets ethically better as it 'develops' and 'progresses' over time.

Atheism is then in this deeper sense atelism - disbelief in a grand plan, pre-destination, fate, teleology. A through-going atheist does not ascribe an inbuilt purpose present at all levels of reality, though of course humans can create their own purposes at their own level.

5) For the religious believer, god is the ultimate authority.

It's no accident that the most authoritarian cultures tend to be the most religious, and have the most oppressive religions.

Thus for the believer, questions of fact are settled not by investigation, or debate, or reasoning - they're settled by authority. If something is true, it's not true because we see it, or intuit it, or reason that it must be so.

It's true because the man in charge says it is. Literally. The act of saying it makes it true - even if no one hears. And even though it has always been true, it didn't become that way until it was said. It's a kind of word magic.

This is an entire epistemology - an entire theory both of how you find the truth, and of what the truth relation itself is.

The truth is whatever god says, therefore whatever the scriptures say, therefore whatever whatever the authorised interpreter of the scriptures says. The priest is infallible - and the priests of other sects are wrong because our priest says so.

When a new priest takes over, truth changes - and some truths of the past retroactively change to falsehoods. In the required doublethink, everything that's currently labeled 'true' has always been and always will be true - but the eternal truths of last week are different from the eternal truths of next week.

This thinking is only possible in a culture or sub-culture where the criterion of authority over-rides all other criteria for deciding what to believe. You can use whatever methods you like to decide on your beliefs about everyday matters, provided all these beliefs are subject to immediate revision on the word of god's mouthpiece.

Except actually, a belief in a god isn't even necessary - just the mouthpiece. It's useful for the human leader to have supernatural backup, but the authoritarian epistemology doesn't need it.

There's a libertarian version of this - supposedly anti-authoritarian - in which every individual has the authority to pronounce on 'their' truth. But in practice it's simply untenable.

The fifth, and I suggest deepest sense of atheism is therefore a rejection of the authoritarian theory of truth.

Those of us who are not cult members still frequently fall into the trap of saying 'It's true because X says it is', and still believing when evidence later casts doubt. To be through-going, we need to get out of this habit.

This doesn't mean automatically disbelieving whatever someone in power says - that would be in itself an authoritarian theory of truth. It just means that authority is the lowest form of evidence.

Now, there is the question of how deep you want your unbelief to be. Deeper is not necessarily better. There is the question of whether radical skepticism is consistently possible, given that humans are social creatures, and societies seem to require power structures by definition.

I've never been to Brazil. My belief that there is such a place relies on not having any good reason to doubt what I've been told about it's existence. In strict logical terms, my default position (the 'null hypothesis') would be provisional disbelief - not even agnosticism on the topic.

Trying to live your whole life like this would be impossible. The practical skeptic is only skeptical about issues they judge important enough to be examined. Plus, there are only so many hours in the day, and so much personal drive.

Humans are remarkably susceptible to the impulse to turn experiences into stories - to see patterns where there are none, to imbue the world with meaning, direction and purpose.

The simple fact that religions are successful suggests that teleological thinking and authoritarian epistemology are easy default positions to slide into. It takes education, some careful thinking and a fair bit of willpower to avoid them.